Bentonite is a versatile mineral,
with an ever-growing number of uses under its belt. Having
struggled in recent years with rising freight costs, the
high-bulk, low-cost mineral has bounced back in 2012 to
increase its global presence in many important industries.
Bentonite is a clay mineral that
expands, absorbing several times its dry mass, in water.
The mineral, sometimes referred to
as fuller’s earth, is composed primarily of
montmorillonite, a mineral of volcanic origin belonging to the
smectite family. Montmorillonite is an aggregate of lamellar
crystals, packed together by electrochemical forces.
Bentonite is mostly appreciated for
its sorptive and thixotropic (water absorption, colloidal,
waterproofing and binding) properties. Due to these varied, yet
inimitable, properties the mineral is widely used in many
different industries, including absorbents, foundry and
oilfields.
Bentonite comes in two main
varieties, each named after their most dominant element:
calcium bentonite and the more commercially important sodium
bentonite.
Sodium bentonite (termed sodium
beneficiation or sodium activation) expands when added to
water. As well as having many other uses, this swelling
property makes the mineral useful as a sealant, lubricant,
coolant, waterproof barrier and a viscosifier.
Calcium bentonite is a useful
adsorbent of ions in solution, as well as fats and oils. The
mineral is the main active ingredient of fuller’s earth,
one of the earliest industrial cleaning agents. Calcium
bentonite can be converted to sodium bentonite by a process
known as ion exchange.
Bentonite market
As with many minerals, demand for
bentonite is driven by end markets. This means that if an end
industry is suffering due to the economic climate, the market
for bentonite also suffers.
For the past few years, the
bentonite market has been affected by the global economic
recession, which has affected many companies across the board,
including those working in foundry for automobiles,
construction and housing.
Some minerals, for example potash,
lithium and bromine, saw similar levels of production in 2010
as in 2008 despite sharp falls in 2009. In contrast, global
production of bentonite fell by a further 5% in 2010 compared
with 2009, in addition to reductions of 9% in the previous
year.
Since 2010, the situation for
bentonite has begun to recover, largely due to the improvements
in its end markets. More than 11m tonnes of bentonite was
produced worldwide in 2011, and global reserves remain in
abundance, with proved reserves found to be more than 10bn
tonnes worldwide, according to the US Geological Survey.
Reserves are mainly distributed
between China, the US, the CIS, Germany, Italy, Japan, Greece,
Brazil, India and Turkey. Most of this bentonite is of the
calcium variety; global sodium bentonite reserves are thought
to be fewer than 500m tonnes.
“The market for bentonite is
mature and can be expected to grow in general relation to
population growth. The market is also cyclical and demand
follows the cycles of energy, housing or other major
indices,” oilfield services leader Halliburton told
IM.
While in the past few years this
mineral has been hit by the global economic climate, it has
also been affected by increasing transport costs. The mineral
has faced difficulty in this area as its low price and high
bulk often make it uneconomical to move long distances. Prices
and sales have been altered accordingly (see table
3).
Bentonite in the oilfield
One of the end markets helping the
bentonite bounce is the oilfields industry, which has grown
significantly in 2012 as governments worldwide look for
alternative energy sources. Many countries have now accepted
the hydraulic fracturing (fracking) process, which is used to
extract natural oil and gas from beneath Earth’s
surface.
The fracking process utilises, in
most cases, a mixture of water, silica sand (or other proppant
variations) and a drilling fluid, such as bentonite. Bentonite
is the second most-commonly used industrial mineral in drilling
fluids, called muds, after barytes. Drilling fluids can be
divided into three primary types: water-based, oil-based and
synthetic. Bentonite is among the most popular of the
water-based fluids, and accounts for around 70-80% of the
drilling grade bentonite produced, and around 20% of overall
bentonite demand.
Sodium bentonite has gained a
stronghold in the oilfield market owing to its viscosifying
characteristics and effective sealing and filtration
properties. These properties come from bentonite’s
structure as colloidal clay, comprising mainly montmorillonite,
meaning the mineral expands when added to water.
Along with gel formation,
bentonite’s role in the oilfield is principally to seal
borehole walls and lubricate the cutting head. This is a small,
yet vital, part of the oil drilling process, meaning
bentonite’s consumption is directly linked to oil and gas
exploration, and therefore demand.
Oilfield bentonite supply and demand
Oilfield rig numbers for 2012 so
far show a slight dip on the counts taken during the
corresponding period 12 months earlier, yet the overall trend
is up on previous years. These rig counts, such as those
published by oilfield service provider Baker Hughes, are
telling barometers for the drilling industry and its mineral
suppliers.
Rig counts back in 2010, just after
the global economic downturn begun to bite, were averaging
2,985 globally. In contrast, for the first 10 months of 2012,
rig counts have averaged 3,536, which is higher than in 2008,
before the recession took hold.
While bentonite resources are
abundant worldwide, the mineral’s use in oilfield drilling
means that stringent requirements are specified by industry
bodies such as the API and OCMA. These requirements often
eliminate many of the potential deposits that could be a
drilling bentonite source.
Despite these specifications, the
crucial role of bentonite cannot be denied in the oilfields
market and its presence is strengthened further by the fact
that it has no close competitors.
“It is not foreseen [that
there is] any significant substitution [for bentonite] from
other materials; on the contrary, in the future bentonite might
be able to substitute other materials, which have less
flexibility than that of bentonite,” S&B Group, which
dedicates 50% of its business to bentonite, told
IM.
The lack of any clear substitutes
for bentonite, and the promising rig counts reported by the
industry, indicate a comfortable future for bentonite in this
market.
Iron ore pelletisation
Another market where bentonite is
widely used is in the pelletising of iron ore. Most pelletising
plants consume this mineral as the main binder as it is low
cost and does not detract from iron ore’s metallurgical
behaviour. The mineral’s absorption properties act by
filling the voids within the pellet matrix with a viscous
gel.
In 2011, a total of 13% of the 4.9m
tonnes of bentonite produced in the US - the world’s
largest producer of the mineral - was used in the iron ore
pelletisation process. However, while the iron ore market is
beneficial to the demand for bentonite, this is yet another
sector that has experienced a knock due to the continuing
financial crisis.
Demand for iron ore has fallen as a
result of weakened economies in China, the US and Europe,
according to the Metal Bulletin Iron Ore Index, which
also reveals that Brazil’s iron ore exports fell 8%
year-on-year in September.
As a result of this slowdown,
global iron ore leader Vale announced in October that it will
suspend operations at three Brazilian iron ore pellet plants,
one West African plant and increase the output of sinter feed.
By suspending operations, Vale removes the capacity responsible
for nearly a fifth of its pellet output seen in the first half
of 2012, which could significantly impact the bentonite
market.
“The company’s decision
to shut down some of its pelletising facilities is a clear
indication of the deterioration in the market for high-quality
iron ore products,” Leonardo Correa, Pedro Grimaldi and
Luiz Fornari, Barclay mining company analysts, wrote in a
report to investors.
“This [operation suspension]
is in response to the evolution of the composition of demand
for raw materials by the steel industry during the economic
cycle, which has shown a reduction in demand for pellets,”
a Vale company statement said.
The market for bentonite in iron
ore pelletisation is expected to improve as we move towards
2013. Positive data from iron ore miners helped fuel the dry
bulk shipping rally in October 2012, while Rio Tinto’s
global iron ore production rose 5% in the fourth quarter to 67m
tonnes. The company expects to produce around a further 250m
tonnes from its operations in Australia and Canada this year,
although this could depend on the weather.
Rival Australian iron ore miner
Fortescue Metals also reported a 30% year-on-year increase in
shipments in Q4. Total production was 16.1m tonnes in the
latest quarter compared with 12.4m tonnes in the corresponding
period last year and 17.8m tonnes in the prior quarter.
Fortescue also forecast iron ore output to hit 36m tonnes in
the next two quarters.
Bentonite
pricing
Bentonite pricing is, as expected,
largely influenced by end-market factors. Both the global
economic slowdown and increasing transportation costs are
having an effect on bentonite supply and demand, as well as
pricing.
“Along with other minerals,
bentonite faces considerable cost pressures due to rising
energy and freight costs,” S&B Group told
IM.
“Furthermore, the high demand
for the mineral required the use of a large exploration
programme into [difficult] mining areas, which also created a
considerable cost increase of the material. As a result,
bentonite prices increased considerably this year more than 8%,
and are expected to increase further next year [allowing] the
producers to be able to cover, at least partially, the
increased costs,” the group added.
These pressures could cause
bentonite prices to increase by as much as 20% by the end of
this year, one industry source told IM. The
market has enjoyed high demand for the past year as oil and gas
exploration has risen which has led to an increase in need for
the oilfield mineral.
Market sources agree that they
expected prices to rise by between 10-20% in 2012 for US
bentonite.
“This seems high, but I know
bentonite producers have been having a hard time keeping ahead
of cost increases,” one source said.
Bentonite in the US is mainly
produced in Wyoming, where a number large producers operate,
and supply is increasingly tight.
Several new producers are expected
to start up operations in Wyoming in 2012/13 to take advantage
of the expected price rise. Wyo-Ben Inc. announced in September
its intention to restart operations at its Meeteetse Draw mine
in the area and US Bentonite is rumoured to be ready to expand
operations from 1 February 2013.
Greek bentonite prices are also
expected to increase, albeit at a more conservative rate.
The market source said he expected
grades to be raised by around 6%. Greek prices currently stand
at between €65-75/tonne (482-95) FOB (dried materials in
bulk).
Although it was unable to disclose
its prices, Italian bentonite producer Sipag Bisalta SpA told
IM that prices are different for each
application due to:
- Bentonite quality;
- Production cost (micronised
products, granular products and so forth);
- R&D cost;
- Technical assistance for
customer; and
- Market (competition).
“Usually, prices for
specialties [feedstuff, spa mud therapy, water treatment,
paper, ceramics, agriculture and winemaking], are higher than
civil engineering bentonite. The foundry market has medium
level prices,” Sipag Bisalta told IM.
Cat litter
One sodium bentonite end market
that has been particularly affected by price increases in 2012
is cat litter, which utilises the mineral due to its absorbent
properties. In the US, more than 900,000 tonnes of bentonite
was sold or used in the pet litter industry in 2010.
However, due to the increased
transport costs experienced across many bentonite end markets,
prices for cat litter were increased throughout 2012.
Oil-Dri Corp. is an example of
this, as the company increased prices on all grades of coarse
and scoopable cat litter in August this year. The US-based
company blamed severely increased transport costs as the main
contributor to the price rises and will use the increased
income to “recover a portion of the margin it has lost
during the past year”, it said.
“[Efforts to control cost
rises] have been dwarfed by the continuous and increasing rise
in transportation costs and other purchased items,” Daniel
Jaffee, Oil-Dri CEO, said.
Oil-Dri produces bentonite and then
processes it into cat litter at its manufacturing facilities in
the US and Canada.
The future for
bentonite
While it is clear that bentonite
has had a rough couple of years coping with the impact of the
global recession and increased transportation costs, the future
looks bright.
Many companies are ploughing ahead
with bentonite production for the main end markets they are
currently working in, while others are looking to expand
production for new markets, which have yet to be explored.
“We are involved in the
further diversification in bentonite applications and in the
extension of regional presence by technology transfer,”
S&B Group told IM.
“A special attention was given
to new products which are linked to environmental benefits and
recycling possibilities. In the drilling market, a new product
has been formulated, which meets highly demanding drilling
conditions,” the company added.
Meanwhile, Halliburton told
IM that it is moving ahead with its drilling
activities as the oilfield market continues to grow.
“In addition to
bentonite’s use as a drilling fluid additive, Halliburton
will continue to explore new opportunities and activities as
they are presented or conceptualised,” the company told
IM.
Sipag Bisalta also plans to be busy
in 2013, and is expanding its range of bentonite products with
chemicals in the civil engineering industry, while also
concentrating on new business outside Italy, the company told
IM.
So, as the world moves out of the global recession and looks
forward to growing business opportunities, it seems that the
bentonite market will also continue to swell.
Bentonite end uses
Sodium bentonite is a mineral with
many end uses and applications but few comparable substitutes.
Below is a list of just a few of bentonite’s most common
applications:
FOUNDRY
Bentonite is used in metal casting
as an inorganic bonding material. The mineral’s ability to
swell and induce viscosity enables sand moulds to flow at a
manageable rate, compact and have thermal stability.
Bentonite’s vitrification temperature is also higher than
many other clays, meaning that when used as an additive in
foundry applications, it makes sand more durable, and, in
particular, more resistant to heat stress.
CIVIL
ENGINEERING
Bentonite is used in civil
engineering as a support fluid in deep foundation construction
due to its viscous properties. Bentonite is also used as a
colloidal additive in cement slurries, to seal off soil
infiltrations and to line the base of landfills.
FEEDS
Bentonite can be used as an animal
feed supplement and, under European regulations, the mineral is
actually classified as a food additive, with E number E558. Due
to its adsorption properties, bentonite is used as a
pelletising aid in the production of animal feed pellets. It is
also able to protect against micotoxins.
WATER
TREATMENT
Due to its ion exchange,
flocculation, and sedimentation properties, bentonite is used
in environmental protection for water clarification and sludge
treatment (see pp. 66-70).
CERAMICS
Bentonite is used to lend
plasticity to the ceramic paste necessary to ensure good
tenacity. Bentonites are selected depending on their use, for
normal mixtures, or white paste, for engobes or enamels.
AGRICULTURE
In agriculture, bentonite can be
mixed with pesticides and fungicides as a support-carrier to
ensure the substance sticks to the target. The mineral can also
be used in organic farming, replacing man-made chemical
substances that are used to inhibit fungi and parasites. This
process is widely used in the biodynamic cultivation of wine
grapes, where bentonite is mixed with other elements to fight
oidium.
In liquid and solid fertilisers,
bentonite is used as a fixing carrier and to control the
release of nitrogen, potassium, and phosphorus. The mineral
also contributes to sludge and manure dehydration and
agglomeration.
CAT LITTER
Due to its absorption properties,
bentonite is a vital ingredient in pet litter. There are two
main types of bentonite cat litter: coarse and scoop-able.
OILWELL
DRILLING
Bentonite is the
second-most-commonly used industrial mineral in drilling fluids
after barytes. The average drilling mud or fluid may consist of
bentonite clay carried in water, diesel or mineral oil.
Bentonite performs several purposes by cooling down the bit,
tubing and the rig itself, while also stabilising the drill
hole, increasing the viscosity of the mud, allowing it to carry
rock cuttings to the surface effectively.
Bentonite also forms a
low-permeability filter cake on the wall of the drilled
borehole that prevents the circulating mud from escaping
through the adjacent formations. When mixed with water,
bentonite disperses to form a colloidal suspension that sets as
a thixotropic gel at concentrations of 1-2% by weight, thus
providing the required viscosity. Bentonite specifications for
use in drilling muds evolved through two organisations: the
American Petroleum Institute (API) and the Oil Companies
Materials Association (OCMA).
IRON ORE
PELLETISATION
Bentonite is widely used in
pelletising of iron ore due to its high temperature resistance
and its ability to not react with the ore. Most pelletising
plants consume this mineral as the main binder as it is low
cost and does not detract from iron ore’s metallurgical
behaviour. The mineral’s absorption properties act by
filling the voids within the pellet matrix with a viscous
gel.